Recently, various apparatuses which use high voltage batteries, such as industrial equipment, home appliances, and vehicles have become more common. Specifically, the high voltage batteries are more actively used in a vehicle technology field.
A vehicle which uses an internal combustion engine using fossil fuel such as gasoline or heavy oil as a major fuel seriously causes environmental contamination such as air pollution. Therefore, recently, people exert great efforts to develop an electric vehicle or a hybrid vehicle, in order to reduce environmental contamination.
The electric vehicle (EV) refers to a vehicle which uses an electric battery and an electric motor without using an oil fuel and an engine. That is, a motor rotates by electricity accumulated in a battery to drive the vehicle. The electric vehicle was developed earlier than a gasoline vehicle. However, the electric vehicle is not commercially used due to problems such as a heavy weight of a battery, a limitation of a battery capacity, and a time to charge the battery. As energy and environmental problems become serious, studies to commercialize the electric vehicle fully start since the 1990s.
In the meantime, recently, as a battery technology rapidly improves, an electric vehicle and a hybrid vehicle (HEV) which adaptively uses a fossil fuel and electric energy are commercially used. Since the HEV uses both gasoline and electricity as a power source, the HEV is positively evaluated in view of improvement of power efficiency and reduction of exhaust gas and is expected to play an intermediate role in evolution to a perfect electric vehicle.
In the HEV and the EV which use the electric energy, a battery in which a plurality of chargeable secondary cells is formed to be one pack is used as a major power source so that no exhaust gas is generated and a noise level is very low.
As described above, in the vehicle which uses the electric energy, the performance of the battery directly affects a performance of the vehicle. Therefore, a battery management system (BMS) which not only measures a voltage of each battery cell, and a voltage and a current of the entire battery to efficiently manage charge or discharge of the battery cell but also monitors a status of a cell sensing IC which senses each battery cell to stably control the cell is acutely required.
FIG. 1 is a block diagram illustrating a battery management system according to a related art.
Referring to FIG. 1, a vehicle battery management system 100 includes a battery pack 10 including a plurality of battery modules, a vehicle electrical system 20, and a battery control device 30.
The battery pack 10 includes a plurality of battery modules 11 and 12. The battery modules 11 and 12 include a plurality of battery cells. The battery stack 10 supplies a charged high voltage DC power to the vehicle electrical system 20 such as a motor.
The battery control device 30 includes a plurality of MCUs 31 and 32 and a BCU 33 which controls the MCUs. The battery control device 30 is connected to the battery pack 10 to monitor a charged/discharged status of the battery pack 10 and controls the charging/discharging operation of the battery pack 10.
As described above, a voltage deviation between battery cells caused by a structural difference is inevitably generated in the battery management system to which the plurality of battery cells is coupled. The voltage deviation hinders uniformity of the voltage of the battery and in turn deteriorates the battery so that a lifespan of the battery is shortened.
Accordingly, a battery cell balancing operation which uniformly maintains a voltage of each cell at the time of operating a system using a battery power or charging and discharging the battery cell is a very important factor of the battery management system.
In the meantime, when collision of the vehicle which uses a high voltage battery or vehicle damage occurs, a leakage current may be generated from the high voltage battery to a chassis of the vehicle. The leakage current of the battery may cause a negligent accident such as fire in the vehicle or electric shock to a driver.
US Patent Unexamined Publication No. 2014-0070772 discloses a technology which detects a vehicle crash to operate a battery cell balancing circuit, and discharge a battery pack.
However, according to the related art, all cells are simultaneously balanced, so that excessive heat which is 100° C. or higher is generated in the balancing circuit and risk of fire or explosion may be raised as problems.